DEBT (Components of Interest Expense) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
2016 Convertible Senior Notes
Debt Instrument [Line Items]
Amortization of the discount on the liability component	$ 7,104,000	$ 6,463,000	$ 5,993,000
Cash interest related to the contractual interest coupon	3,342,000	3,218,000	3,154,000
Total	10,446,000	9,681,000	9,147,000
Amortization of debt discount, capitalized interest	900,000	1,000,000	1,100,000
Cash interest related to contractual interest coupon, capitalized interest	400,000	500,000	600,000
2012 Senior Convertible Notes
Debt Instrument [Line Items]
Amortization of the discount on the liability component	0	0	2,527,000
Cash interest related to the contractual interest coupon	0	0	1,378,000
Total	0	0	3,905,000
Amortization of debt discount, capitalized interest			500,000
Cash interest related to contractual interest coupon, capitalized interest			$ 300,000